Compressor controlling mechanism



June 20, 1933. J, CLAPP 1,914,544

COMPRESSOR CONTROLLING MECHANISM Filed Aug. 20, 1928 Patented June 2 0,11933 UNITED STATES PATENT OFFICE LEWIS J. .CLAPP, OF CLABEMIONT, NEWHAMISHIBE, ASSIGNOR '10 SULLIVAN MACHINERY COMPANY, A CORPORATION OFMASSAGHUSETTS COMPRESSOR CONTROLLING KEGHANISM j l Application filedAugust 20, 1928. Serial No. 300,860.

My invention relates to a controlling mechanism for a compressor. Moreparticularly, the invention relates to a mechanism for controlling theloading and unloading of a compressor. The principles of my inventionmay with advantage be employed in a mechanism adapted automatically tounload a compressor so that its driving motor may start without havingto drive a fully loaded compressor.

One object of my invention is to provide an improved controllingmechanism for the loading and unloading of a compressor. A furtherobject of my invention is to combine with the electrical connections ofan electric motor which drives a compressor improved mechanism forholding the compressor unloaded until the motor has been started. Otherobjects and advantages of the invention will be clearly apparent fromthe following description, and more particularly pointed out in theclaims.

An illustrative embodiment of the invention is shown in the drawing,ofwhich,

Fig. l is a diagrammatic view showing the compressor and motor in sideelevation, and including a diagram of the electrical connections for themotor.

- Fig. 2 is a side, elevation of the solenoid which, according to thisillustrative embodiment, controls a spring which forms a part of thepilot valve mechanism for controlling unloading of the compressor. Inthis view the cover is broken away to expose the solenoid and pilotvalve.

Fig. 3 is a section on line 3-3 of Fig. 4.

Fig. 4 is a section on line 4-4 ofFig. 2.

In Fig. 1 there is shown an electric motor 8 driving a compressor 9.Although it will be understood that my invention is applicable to any ofthe usual types-of compressors, .there is disclosed herein a compressorof the vertical, two cylinder type, which is provided with suitablepistons and inlet and discharge valves. The fluid bhing pumped may beair; and in such case, the same is drawn in through an air filter 10.The fluid being pumped is discharged from the compressor through asuitable pipe connection (not shown) to a receiver tank 11,

from which it may be supplied for any desired purpose. I haveillustrated a simple three-pole switch 12 for controlling the sup-.under the control also of a manually operable switch, so that theoperator may himself control the starting and stopping of the motor Aswitch 17 is also provided, as is customary, so that the connection withthe outside source of power may be made or broken at any time by'theoperator.

A. suitable pressure operated switch 18 is connected by a pipe 19 to thereceiver tank 11. As pressufia switches of this type are well known inthe art, the details of the same have not been illustrated herein.Preferably a switch will be selected which will open and close withinthe desired limits of pressure, closing a circuit when the desiredminimum pressure is reached and breaking it when the maximum isattained. The pressure switch 18 is included in a control circuit 19' towhich energy is supplied from the main line through a small transformer20. This control circuit includes the solenoid 16 and accordingly theflow of current through the solenoid 16 may be controlled by thepressure switch 18. In the embodiment illustrated in Fig. 1 the solenoid16 operates when energized to connect the motor with the main line.Accordingly, when receiver pressure lowers to the minimum desired, theswitch 12 is closed and motor 8 started, and when the maximum is reachedthe switch 12 is opened and the motor stopped.

The above describedoperation of the control circuit occurs when'theswitch 21 (of the manually operable type) is closed. Should, however, itbe desired to manually control the solenoid 16, a second manually oerable switch 22 may be closed to energize the solenoid 16. It will benoted that the switch 22 is connected in parallel with the pressureswitch 18. Various combinations of manual and automatic control for thesolenoid 16 will be obvious from the" above description of this controlcircuit.

The mechanism. employed for unloading and loading the compressor may beof the type disclosed in Fig. 4 of my Patent Ifl'o. 1,657,200, datedJanuary 24, 1928, to which reference should be hadfor a fullerdescription of the mechanism.

Only general features of the pilot valve shown in Figs. 2 and 3 will bedescribed herein, as a full description of this ilot valve may be foundin the patent to onrader, No. 1,601,943, dated October 5, 1926.

A pipe 23 supplies fluid under pressure from the receiver tank to thepressure chamber 46 of the ilot valve mechanism 24. A movable va vemember 47 within the pilot valve mechanism 24 is ada ted, in oneposition, to supply pressure fluid throu h the connection 25 to the comressor un oading mech'- anism, and, in anot er osition to vent theconnection 25 to atmosp ere. A pin 28, associated with said movablemember 47 in a supporting relation, projects through the end of thecasing of the pilot valve mechanism 24 and bears against a. lever 26. Aspring 27, when under tension,'pulls the lever 26 against said pin 28. Aloo 29 at one end of said spring engages one o a plurality of serrationsin the lever 26. A loop 30 at the other end of the spring 27 engages anotch in a screw 31 which projects through a yoke 32. A nut 33 holds thescrew 31 in adjusted position and rmits adjustment thereof. The yoke 32as a pair of long arms 34 braced by a rivet 35 and sleeve 45, andsecured to the core 36 of a solenoid 37. A circuit 38, connected at and41 to two of the main line connections for the motor, supplies currentto energize the solenoid and force the core 36 to the left. A time delayrelay 39 is interposed in the circuit 38 to cause a predeterminedinterval of time to elapse between the beginnin of current flow throughthe main line am? the energizing of the solenoid 37. It will be notedthat the operatin devices for the time relay 39 are energize by acircuit in parallel with the solenoid 37 and deriving current from theconductors connected at 40' and 41 to two of the main power connectionsfor the motor.

Whenever the switch 12 is open, the solenoid 37 is de-energized,-and thespring 27 does' not perform its function of holding the lever 26 firmlyagainst the pin 28. A free passage is therefore afforded the fluid inthe receiver to pass throughpipes 23 and 25 to the unloading mechanismto hold the compressor unloaded. Therefore, the compressor is alwaysunloaded when the motor is not running. It should be noted that whenpressure in the receiver 11 falls solow that the unloading mechanism isrot actuated, the compressor is in efiect unloaded because there is nosubstantial pressure against which the piston of the compressor needsact.

Assuming that the motor 8 is started up, either due to the closure ofthe automatic pressure switch 18, or to closure of the manually operableswitch 22, then the time dela relay is set in operation; and as the preetermined interval elapses, the solenoid 37 isenergized so as to forcethe core 36 to the left and apply the pro er spring pressure to thelever 26. Shoulthe pressure in the receiver 11 be low, the pilot valve24. will function to load the compressor by venting pressure fluid fromthe pipe connection 25.

Assumin that the compressor is running, and that t e switch 21 is closedand the switch 22 open, the solenoid 16 is now under the control of theautomatic pr 'ure switch 18. Should the pressure in th receiver 11exceed the pressure for which the switch 18 is set, current will be cutoff from the solenoid 16 to disconnect the motor from the main line.Immediately the solenoid 37 is de-energized, and the core 36 moves tothe right so as to relieve the pressure exerted r by the spring 27. Themovable valve member 47 within the pilot valve mechanism 24 is now freeto move so as to supply pressure fluid through the connection .25 tounload the compressor, and so moves. f

It is therefore apparent that whenever the motor 8 is stopped thecompressor is unloaded. When the supply of fluid in the receiver tank 11has been sufiiciently depleted to cause actuation of the automaticswitch 18, the supply of current through the control circuit 19 isrestored and the solenoid 16 energized so that the switch 12 is closed.The motor is at once started, and after a predetermined time interval,during which the motor 8 is ermitted to come up to speed, the 'solenoi37 is energized. The pilot valve 24 is now restored to operativecondition and the compressor is again loaded. Whenever the solenoid 16is to be controlled only by the ressure switch 18, the tension of spring27 s ould be so adjusted that the compressor will" not unload before theswitch 18 opens, and will not fail to reload when the switch 18 closes.By proper adjustment the spring 27 may serve as a safety device,insuring unloading should the device 18 not stop the motor when themaximum desired pressure is reached.

Assuming that the switch 21' is open, the solenoid 16 will be under thecontrol of the manually operable switch 22.. By closing this switchthe-operatormay start the motor, since the solenoid will pull the switch12 into closed position. The motor, however, has suflicient time to comeup to speed before loading takes place, since the solenoid 37 is notenergized until a predetermined time interval has elapsed. It does notnecessarily follow, however, that when the solenoid 37 is energized thecompressor is immediately loaded, since the movement ofthe yoke 32 tothe left merely restores the pilot valve 24 to operative condition. Thecompressor now runs loaded or unloaded, dependent upon whether thepressure in receiver 11 is sufiicient to force the movable member 47 tothe right so as to deliver fiuid throu h the connection to actuate theunloading mechanism of the compressor, or whether the sprmg 27 overcomesthe receiver pressure and holds the movable member 47 in the positionshown in Fig. 3.

' The motor now continues to run so long as the switch 22 is closed;andthe compressor is loaded and unloaded automatically through theagency of the pilot valve 24 as the pressure in the receiver tank fallsand rises. It is obvious therefore that while the motor is under thecontrol of the manually operable switch 22, the spring 27 may beadjusted so as to cause loading and unloading at such pressures (withinthe capabilities of the mechanism) as are desired.

My invention improves the efliciency of the compressor, and in animproved manner functions to automatically unload the compressor whenthe motor is stopped. The solenoid which in this illustrativeembodim'ent isemployed in the control system, is so combined withelements of the pilot valve as to insure that this pilot valve can notfunction to load the compressor during such time as current is cut offfrom the compressor driving motor.

\Vhile I have in this application specifically described one form whichmy invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration and that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claims.

What I claim as new and desire to secure b Letters Patent is:

1. In combination, a compressor having an unloader adapted in oneposition to unload and in another position to load said compressor, saidunloader being pressure fluid actuated, a driving motor for saidcompressor, a pilot valve for controlling the supply of actuating fluidto said unloader comprising a valve member adapted in one position toopen communication of the supply of actuating fluid to said unloader andin another position to vent the fluid previously supplied, said valvemember having means including a surface subject to compressor dischargepressure for normally biasing said valve member toward unloadingposition, resilient means for normally biasing said valve member towardloading position, a movable member against which said resilient meansreacts, and means for controlling said movable member automatically inaccordance withthe stopping and starting of said (lllV- ing motor.

2. In combination, a compressor, 'a drlving motor therefor, means forunloading said compressor, a pilot valve responsive to compressordischarge pressure for controlling said compressor unloading means,-sa1dpilot valve comprising a movable member having a surface sub ected tocompressor discharge pressure an resilient means for normally supportingsaid movable member in opposition to said compressor discharge pressure,a second movable member against which said resilient means reacts, andmeans for controlling said second movable member automatically inaccordance with the stopping and starting of said driving motor.

3. In combination, a compressor, an electric driving motor therefor,means for unloading said compressor, means for controlling saidcompressor unloading means comprising a movable member having a surfacesubjected to compressor discharge pressure, resilient means for normallysupporting said movable member in opposition to said compressordischarge pressure, and a member against which said resilient ,meansreacts, said member being movable to supporting position upon flow ofcurrent to said compressor driving motor and movable to oppositeposition when no current is flowing thereto.

4. In combination, a compressor, a driving motor therefor, means forunloading said compressor, means for controlling said compressorunloading means comprising a movable member having a surface subjectedto compressor discharge pressure, said member movable to effect loadingand unloading, resilient means for normally supporting said movablemember in opposition to said compressor discharge pressure during loadedoperation, a solenoid, means whereby said solenoid is controlledautomatically in accordance with the stopping and starting of saiddriving motor, and a second movable member actuated by said solenoid andagainst which said resilient means reacts.

5. In controlling mechanism for a motor driven compressor, thecombination with a pilot valve comprising a movable member iaving asurface subjected to fluid pressure, and tending to move the same in onedirection, resilient means for normally supporting said movable memberin opposition to said fluid pressure, to render the same responsive to apressure in excess of a desired maximum, of a solenoid, and a secondmovable member actuated thereby against which said resilient meansreacts.

6. In controlling mechanism for a motor driven compressor, thecombination with a pilot valve comprising a movable member aving asurface subjected to fluid pressure tending to move said member in onedirection, and means comprising a spring for normally supporting saidmovable member in-opposition to said fluid pressure to render the sameres onsive to a pressure in excess of a desire maximum, of a solenoid,and a second movable member actuated thereby and cooperating with saidspring, said secondmovable member when in one position maintainin said sring in supportmg condition and in anot er position permitting saidspring to relax.

7. In controlling mechanism for a motor driven compressor, thecombination with a pilot valve comprising a movable member having asurface subjected to fluid pressure tending to move said member in onedirection, and means comprising a lever and a spring for normallysupporting said movable member in op )osition to said fluid pressure, ofa solenoid, and a longitudinally movable member actuated thereby andconnected to said spring, said movable member when in one positionmaintaining said spring in supporting condition and in another positionpermitting said spring to relax.

8. In combination, a compressor, means for unloading said compressor, adriving motor for said com ressor, and means for controlling the loa ingand unloading of said compressor comprising a movable member whosemovements control loading and unloading, said member having a surfacesubjected to compressor discharge pressure, and resilient meanscooperating with said movable member, the compressor discharge pressuretending to move said member in a direction to cause unloading of thecompressor and the resilient means tending to move the same in adirection to cause loading of the compressor, a movable member againstwhich said resilient means reacts, and means for controlling saidmovable ,member automatically in accordance with the stopping andstarting of said driving motor.

9. In combination, a compressor, means for unloading said compressor, adriving motor for said compressor, means for controlling the loading andunloading of said compressor comprising a movable member with a surfacesubjected to compressor discharge pressure, and resilient meanscooperating with said movable member, movements of said membercontrolling loading and unloading and the compressor discharge pressuretending to move said member in a direction to cause unloading of thecompressor and the resilient means tending to move the same in adirection to cause loading of the compressor, pressure responsive meansfor controlling the stopping and starting of said driving motorautomatically in accordance with the variations in the dischargepressure of said compressor, a movable abutment member for saidresilient means, and means whereby the position of said abutment memberis controlled by stopping and starting of said driving motor.

10. In combination, a compressor, means for unloading said compressor, adriving motor for said compressor, means for controlling loading andunloading of said compressor comprising a movable member with a surfacesubject to compressor discharge pressure, and resilient means cooperatinwith said movable member, means governe by movements of said membercontrolling loading and unloading, the compressor discharge pressuretending to move said member in a direction to cause unloading of thecompressor and the resilient means tending to move the same in adirection to cause loading of the compressor, pressure responsive meansadapted to control the starting and stop ing of said motor automaticallyin accor ance with variations in the discharge pressure of saidcompressor, manually operable means adapted to start or stop said motorat will, either of said motor controllin means being selectivelyconnectible to sai motor to control the same, a movable abutment memberfor said resilient means, and means whereby the position of saidabutment member is controlled by starting and stopping of said drivingmotor.

11. In combination, a compressor, means .for unloading said compressor,an electric motor for driving said compressor, means "for controllingloading and unloading of said compressor com rising a movable memberwith a surface su ject to compressor discharge pressure, and resilientmeans cooperating with said movable member, means governed by movementof said member controlling loading and unloading, the compressordischarge pressure tending to move said member in a direction to causeunloading of the compressor and the resilient means tending to movethe-same in a direction to cause loading of the compressor, a pressureswitch adapted to control the starting and stopping of said motorautomatically in accordance with variations in the discharge pressure ofsaid compressor, a manually operable switch adapted to start or stopsaid motor at will, either of said switches being conneetible at will tocontrol said motor. a solenoid having a core; member providing anabutment for said resilient means, and means whereby the position ofsaid core is automatically controlled by starting and stopping of saiddriving motor.

12. A controlling mechanism for a prime mover driven compressor havingunloading means, comprising, in combination, means for controllingactuation of said unloading means in accordance with compressordischarge pressure, and means for rendering said controlling meansinherently operative automatically in accordance with operation of theprime mover.

13. A controlling mechanism for a unit havin a prime mover drivencompressor rovi ed with unloadin means, comprising, 1n combination,means or controlling actuation of said unloading means in accordancewith compressor discharge pressure, and means for rendering saidcontrolling means inherently operative automatically in accordance withnormal operation of said unit.

14. A controlling mechanism for a unit havin a prime mover drivencompressor provi ed with unloading means, comprising, in combination, apilot valve adapted to be actuated by compressor dischar e pressure toeffect operation of said unloa in means, and means cooperating withsaidpi 0t valve for renderin the same inherently opera- -tive automaticallyin accordance with normal operation of said unit.

15. A controlling mechanism for a unit havin a prime mover drivencompressor provi ed with unloading means, comprlsmg, in combination, apilot valve adapted to be actuated by compressor dischar e pressure toeffect operation of said un oadin means, and means cooperating with saipilot valve for rendering the same inherently operative automatically inaccordance with normal operation of said unit, said latter meansincluding a solenoid adapted when energized to effect said inherentoperativeness of said pilot valve.

16. A controlling mechanism for a unit havin a prime mover drivencompressor provi ed with unloading means, compris- 1n in combination, apilot valve adapted toTe actuated by compressor dischar e pressure toefiect operation of said an oading means, and means cooperating with saipilot valve for rendering the same inherently operative automatically inaccordance with normal operation of said unit, said latter meansincluding a solenoid, and a yieldable connection between said solenoidand pilot valve whereby upon energization of said solenoid the inherentoperativeness of said pilot valve is effected.

17. The combination comprising a unit havin a prime mover drivencompressor provi ed with unloading means, mechanism for controllingactuation of said unloadingl means automatically in accordance witcompressor discharge pressure, and means for rendering said controllingmechanism inherently operative automatically in accordance with normaloperation of the unit, said latter means having a device actuated by thesupply of power to the prime mover.

18. The combination comprising a unit havin an electric motor driven comressor provi ed with unloading means, 'mec anism for controllingactuation of said unloading means automatically in accordance withcompressor discharge pressure, and electrically controlled means. forrendering said controlling mechanism inherently operative automaticallyin accordance with a predetermined condition of the unit.

19. The combination comprising a unit having an electric motor drivencompressor provided with unloading means, mechanism for controllingactuation of said unloading means automatically in accordance withcompressor discharge pressure, and electrically controlled means forrendering said controlling means inherently operative automatically inaccordance with a predetermined condition of theunit, said electricallycontrolled means havin provision for being supplied with current rom thesame source as that from which said electric motor is supplied.

20. In a pilot valve mechanism, a movable controlling member having asurface subjected to a pressure to be controlled, said member operativewhen moved in a predetermined manner to efiect a control, resilientmeans for opposing movement of said member in response to the pressureto be controlled, an element movable to stress said resilient means torender said member inoperative to affect its said control except whenpredetermined pressure conditions exist, means automatically limitingthe stress imposable by movement of said element to the desired amount,and means for moving said element to stress said resilient means.

21. In combination with a motor driven pump, controlling mechanismincluding a controlling member having a surface subjected to pumpdischarge pressure, said member operative when moved in a predeterminedmanner to effect a control, resilient means for opposing movement ofsaid member in response to ump discharge ressure, an element movable tostress sai resilient means to render said member inoperative to effectits said control except when a predetermined maximum pump dischargepressure exists, means for automatically limiting the stress imposed bymovement of said element, and means for moving said element to stresssaid resilient means only when the comgressor is driven at apredetermined s ee 22. In a controlling mechanism for a mo- ,tor drivencompressor, the combination with a pilot valve comprising a movablemember, variations in whose position determine the operation of saidvalve, said member having a surface subject to fluid pressure, andresilient means for normally supportin said movable member in oppositionto sai fillld pressure during normal loaded running of said compressor,of a movable member against which said resilient means reacts, andactuating meansfor said second mentioned movable member controlled inaccordance with the speedof the compressor.

23. In a controlling mechanism for a motor driven compressor, thecombination with a pilot valve comprisin a movable membcr having asurface su ject to fluid pressure and resilient means for normallysupporting said movable member in opposition,

to said fluid pressure during normal loaded running of said com ressor,of a movable member against whic said resilient means reacts, andactuating means for said second mentioned movable member controlled inaccordance with the speed of the compresso: said second mentionedmovable member when in one position maintaining said spring insupporting condition and in another position relieving the stress of thesprin".

24. In a controlling mechanism for a motor driven compressor, incombination, in a pilot mechanism, a movable member changes in whoseposition effect control by said pilot mechanism, said member having asurface subject to fluid pressure, and a spring for normally supportingsaid movable member in opposition to the fluid ressure, of a secondmovable member a ined with said spring and movable to impose a stress onthe latter to cause the same to support the first mentioned movablemember in opposition to the fluid pressure, and actuating means for saidsecond mentioned movable member controlled in accordance with the speedof the compressor.

25. In a controlling mechanism for a motor driven compressor, incombination, in a pilot mechanism, a movable member changes in whoseposition effect control by said pi of; mechanism, said member having asurface subject to fluid pressure, and a spring for normally supportingsaid movable member in opposition to the fluid pressure, of a secondmovable member alined with said spring and movable to impose a stress onthe latter to cause the same to support the first mentioned movablemember in. opposition to the fluid pressure, and actuating means forsaid second mentioned movable member controlled by the speed of thecompressor including a solenoid energized as the compressor reachesnormal running speed.

26. In a controlling mechanism for a motor driven compressor, incombination, in a pilot mechanism, a movable member chan es in whoseposition effect control by said pi ot mechanism, said member having asurface subject to fluid pressure, and a spring for normally supportingsaid movable member in opposition to the fluid )ressure, of a secondmovable member aligned with said 5 ring and movableto impose a stress ontile latter to cause the same to support the first mentioned movablemember in op osition to the fluid pressure, and contro ling means forsaid second movable member including a solenoid and means for limitingthe movement thereof by said solenoid.

27. In a pilot valve mechanism, in combination, a valve casing havingconnections for receiver pressure and for a receiver pressure actuatedunloading device, a valve in said casing controlling communicationbetween said connections. and means for maintaining said valve closeduntil receiver pressure reaches a desired maximum and closing the sameupon a predetermined dro below said maximum including a solenoienergized during normal controlling operation of said valve continuouslyboth in the open and in the closed positions of the latter.

28. In a pilot valve mechanism, in combination, a valve casing havingconnections for a source of pressure to be controlled, to atmosphere,and for a pressure 0 erable unloading device, valve means for c osingcommunication between the first and third con.- nections and openingcommunication between the second and third when the pressure to becontrolled is below a desired value and automatically reversing suchconnections when such value is reached including a solenoid energizedduring normal controlling operation of said valve continuously in bothof said positions of said valve.

29. In a ressure responsive controlling mechanism or a compressor or thelike, in combination, a valve casing having a connection with a sourceof controlling pressure and a connection to a device to be controlled, avalve in said casing, means for subjecting said valve to saidcontrolling pressure to provide an actuating force therefor, andelectro-magnetically controlled means for providing an opposing forceadequate to prevent valve movement only until the controlling pressurereaches a desired value and upon the attainment of said value, thoughstill exerted, to be overcome by the valve actuatin force.

30. In combination, a pump a driving motor therefor, said pump havmunloadin means, and means for control ing actuation of said unloadingmeans automatically in accordance with pump discharge pressurevariations including a solenoid energized continuously both duringloaded and unloaded operation of said ump at such speed, when said pumpis driven at normal operating speed.

31. In combination, a pump, a driving motor therefor,-said pump havmunloading means, and means for controlling actualOf.

tion' of said unloading means automatically in accordance with pumpdischarge pressure variations to control the quantity of fluid deliveredby said pump during periods of continuous driving thereof 'by said motorincluding a solenoid and means for energizing the same when the pumpattains normal operating speed and maintaining the same energized duringcontinued drive of said pump.

In testimony whereof I afiix my signature.

' LEWIS J. CLAPP.

